Nowadays, printed-circuit boards are frequently assembled in a holder or rack having the shape of an open-topped box whose sidewalls form tracks for the guidance of the boards into and out of their assembled position in which terminal tabs on a base strip or block of each board fit into a socket having coacting contacts to complete a connection to an external circuit. (In practice, the track-forming sidewalls may be horizontally disposed, with the contact-bearing sockets arranged on the upright rear wall.)
The emplacement of such printed-circuit boards in their holder is a somewhat delicate operation since in the last phase thereof an additional thrust must be exerted in order to interfit the coacting connector pairs of which there could be several tens per board. In view of the great frictional resistance, attempts to insert a board with the bare hands may cause injury to the operator whose fingers could be cut by the exposed front edges of the board when applying pressure thereto. It is also important to hold the board properly aligned with its guide channels in order to avoid bending stresses which could damage the printed circuits. Extracting the inserted board again poses problems since the abrupt reduction of the frictional resistance upon disengagement of the connectors may lead to an accelerated withdrawal motion deviating from straight linearity. These difficulties are only partly obviated by conventional manipulators of which we are aware.